Yet, little is known about the Major Baltic Inflows (MBIs) entering the Eastern Gotland Basin (EGB) and

how they propagate towards the Northern Gotland Basin (NGB) and beyond, especially towards the Gulf

of Finland (GoF). This is due to several reasons. First, big inflow events are relatively scarce. Since the

1980s inflow activity has decreased dramatically and simultaneously hypoxia in the deep waters have

widely spread. Second, the temporal and spatial resolution of the measurements made from the last

MBIs were not really sufficient. However, a detailed study of the current MBI is particularly important for

the understanding of the coupling of these basins. The recent MBI from December 2014, which is the

third biggest inflow since 60 years (estimated volume 318 km³), gives us the unique opportunity to take a

detailed snapshot of the physical and biogeochemical consequences. High-quality CTD-measurements

taken along the way from the Gotland Basin (GB) through the Northern and Western Gotland Basin and

further to the GoF during the proposed cruise will form the basis of this study. We are going to assess

how the remaining saline and oxygen rich water masses of the MBI are distributed in the central and in

the northern Baltic, how the properties of the hydrological regime have changed, whether a new

stagnation period and the return of hypoxic conditions already started, and in which way the oxygen

distribution in the Deepwater is affected. Furthermore a second cruise with leading Estonian, German

and Polish scientists at the same time will also reveal measurements (e.g. towed CTD) in this area and

therefore will complement the data set which will be obtained by the Salme expedition. In summary, both

cruises will provide high-resolution data of the undersampled transition zone between the EGB and the

GoF. Ultimately, this work will shed new light in the development of MBIs in their final stage and will

investigate their impact on the GoF region.